In a general sense, the invention is directed to systems and methods for treating interior tissue regions of the body. More specifically, the invention is directed to systems and methods for treating dysfunction in and around the lower esophageal sphincter and cardia of the stomach, and, in particular, hernias of the stomach through the esophageal hiatus and diaphragm, commonly called hiatal hernias.
A. The Gastrointestinal Tract
The gastrointestinal tract, also called the alimentary canal, is a long tube through which food is taken into the body and digested. The alimentary canal begins at the mouth, and includes the pharynx, esophagus, stomach, small and large intestines, and rectum. In human beings, this passage is about 30 feet (9 meters) long.
Small, ring-like muscles, called sphincters, surround portions of the alimentary canal. In a healthy person, these muscles contract or tighten in a coordinated fashion during eating and the ensuing digestive process, to temporarily close off one region of the alimentary canal from an other.
For example, a muscular ring called the lower esophageal sphincter (or, in shorthand, LES) surrounds the junction of the esophagus and the stomach. The lower esophageal sphincter is a ring of increased thickness in the circular, smooth-muscle layer of the esophagus. Normally, the lower esophageal sphincter maintains a high-pressure zone between fifteen and thirty mm Hg above intragastric pressures inside the stomach.
The stomach muscles churn the food and digestive juices into a mass called chyme. Then the muscles squeeze the chyme toward the pyloric (intestinal) end of the stomach by peristaltic waves, which start at the top of the stomach and move downward. The pyloric sphincter, another ringlike muscle, surrounds the duodenal opening. The pyloric sphincter keeps food in the stomach until it is a liquid. The pyloric sphincter then relaxes and lets some chyme pass into the duodenum.
When a person swallows food, muscles of the pharynx push the food into the esophagus. The muscles in the esophagus walls respond with a wavelike contraction called peristalsis. The lower esophageal sphincter relaxes before the esophagus contracts, and allows food to pass through to the stomach. After food passes into the stomach, the lower esophageal sphincter constricts to prevent the contents from regurgitating into the esophagus.
B. Gastrointestinal Tract Sphincter Dysfunction
Dysfunction of a sphincter in the body can lead to internal damage or disease, discomfort, or otherwise adversely affect the quality of life. For example, if the lower esophageal sphincter fails to function properly, stomach acid may rise back into the esophagus. Unlike the stomach, the esophagus has no natural protection against stomach acids. When the stomach contents make contact with the esophagus, heartburn or other disease symptoms, including damage to the esophagus, can occur.
Gastrointestinal reflux disease (GERD) is a common disorder, characterized by spontaneous relaxation of the lower esophageal sphincter. It has been estimated that approximately two percent of the adult population suffers from GERD. The incidence of GERD increases markedly after the age of 40, and it is not uncommon for patients experiencing symptoms to wait years before seeking medical treatment.
GERD is believed to be caused by a combination of conditions that increase the presence of acid reflux in the esophagus. These conditions include transient LES relaxation, decreased LES resting tone, impaired esophageal clearance, delayed gastric emptying, decreased salivation, and impaired tissue resistance. Because the resting tone of the lower esophageal sphincter is maintained by both myogenic (muscular) and neurogenic (nerve) mechanisms, some believe that aberrant electrical signals in the lower esophageal sphincter or surrounding region of the stomach (called the cardia) can cause the sphincter to spontaneously relax.
Lifestyle factors can also cause increased risk of reflux. Smoking, large meals, fatty foods, caffeine, pregnancy, obesity, body position, drugs, hormones, and paraplegia may all exacerbate GERD.
The excessive reflux experienced by patients with GERD overwhelms their intrinsic mucosal defense mechanisms, resulting in many symptoms. The most common symptom of GERD is heartburn. Besides the discomfort of heartburn, reflux results in symptoms of esophageal inflammation, such as odynophagia (pain on swallowing) and dysphagia (difficult swallowing). The acid reflux may also cause pulmonary symptoms such as coughing, wheezing, asthma, aspiration pneumonia, and interstitial fibrosis; oral symptoms such as tooth enamel decay, gingivitis, halitosis, and waterbrash; throat symptoms such as a soreness, laryngitis, hoarseness, and a globus sensation; and earache.
Complications of GERD include esophageal erosion, esophageal ulcer, and esophageal stricture; replacement of normal esophageal epithelium with abnormal (Barrett""s) epithelium; and pulmonary aspiration.
C. Other Dysfunction (Hiatal Hernia)
Normally, the diaphragm wraps about the LES, forming between it and the LES an aperture called the esophageal hiatus. Below the diaphragm, and still within the esophageal hiatus, two tendonous and muscular structures, referred to commonly as left and right crura also surround the LES.
The right crura and the left crura connect to the spine, generally at the second and fourth upper lumbar vertebra. The crura pass forward and inward and eventually diverge so as to surround the esophagus and LES.
A hiatal hernia develops when the entire LES moves upward away from the crura. The LES and part of the upper stomach push upward through the esophageal hiatus, and protrude above the diaphragm into the chest cavity.
A hiatal hernia may occur if the crura become weakened, or if a weakened region of the crura is accompanied with coughing, vomiting, straining during bowel movements, sudden exertion, pregnancy, or obesity. Occasionally, a hiatal hernia becomes large enough to allow as much as one-third or more of the stomach to protrude through the diaphragm. This can exert pressure on the lungs or diaphragm, making it difficult to breathe normally.
Hiatal hernia frequently accompanies severe GERD. The hernia may increase transient LES relaxation and delay acid clearance due to impaired esophageal emptying. Thus, hiatal hernias may contribute to prolonged acid exposure time following reflux, resulting in GERD symptoms and esophageal damage.
The herniated or enlarged portion of the stomach cavity can serve as a reservoir to collect refluxed stomach acid, and provide a readily available source of acid into the esophagus, thus intensifying the negative effects of gastrointestinal reflux disease (GERD). It is estimated that as many as 25%-50% of people older than 50 years suffer from hiatal hernias, although hiatal hernias may afflict sufferers at any age.
Hiatal hernias are often accompanied by painful burning sensations in the chest region, and the pain often intensifies on a full stomach or during pregnancy. Additionally, hiatal hernias are known to aggravate heartburn, and exert pressure on the lungs or diaphragm, causing breathing and swallowing difficulties.
In severe cases, hiatal hernias can create friction that cause lesions within the stomach. The lesions can bleed and lead to iron-deficiency anemia from chronic loss of blood. In the most severe cases, a large percentage of the stomach could protrude into the chest cavity, causing restricted blood flow to the stomach.
Hiatal hernias are presently treated with a variety of approaches. In less severe cases, no treatment may be necessary. Increasing in severity, lifestyle changes including dietary changes and quitting smoking may lessen the painful effects of a hiatal hernia.
With moderate cases, antacids are used to neutralize the stomach acid and reduce inflammation. Pepcid, Reglan, and Brevital are some common medicines, trade names for famotidine, metoclopramide, and methohexital, respectively.
In moderate to dangerously severe cases, invasive abdominal surgical intervention may be required to move the LES and crura into proper orientation with the diaphragm. The traditional method is an invasive surgery whereby an incision is made through the abdominal wall. The bulging tissue is returned to the abdominal cavity. The crura are re-approximated, and the fundus of the stomach is wrapped around the LES, thus securing the stomach in the proper intra-abdominal position. No implant is used for this repair.
Although these methods can capably treat hiatal hernias in certain instances, all surgical intervention entails making an incision into the abdomen and carry with it the usual risks of abdominal surgery.
One aspect of the invention provides systems and methods for treating tissue in the crura. The systems and methods introduce a catheter tube into a region of the esophagus adjoining the crura. The systems and methods advance a tissue penetrating element from the catheter tube through a wall of the esophagus and into contact with tissue in one or more crura. The tissue penetrating element is operated, e.g., to affect a tightening of the crura.
The tissue penetrating element can be operated in various ways to achieve this result. For example, the tissue penetration element can ablate the contacted tissue, e.g., by use of an ablating agent or by the application of energy (such as radio frequency energy) to the contacted tissue to form a lesion. Alternatively, the tissue penetrating element can staple or suture the contacted tissue to tighten the crura. Still alternatively, the tissue penetrating element can deliver an agent to the contacted tissue to affect tightening, e.g., a tissue bulking agent, a tissue growth factor, fibrosis inducer, fibroblast growth factor, or scerosant.
Another aspect of the invention provides systems and methods for treating hiatal hernia. The systems and methods locate the stomach in a proper intra-abdominal position below the diaphragm, and introduce a catheter tube into a region of the esophagus adjoining the crura. The systems and methods advance a tissue penetrating element from the catheter tube through a wall of the esophagus and into contact with tissue in one or more crura. The systems and methods tighten the one or more crura using the tissue penetrating element, to thereby retain the stomach in the proper intra-abdominal position.
Features and advantages of the inventions are set forth in the following Description and Drawings, as well as in the appended Claims.